Explain the Hypermetropia with the help of diagram.

Explanation

1) A person with hypermetropia can see distant objcts clearly but cannot see objects at near distances. This is also known as 'Far sightedness'.
2) Eye lens can be form a clear image on the retina when any object is placed beyond near point.
3) To correct the defect of hypermetropia , we need to use a lens which forms an image of an object beyond near point at H. When the object is between H and L. This is posible only when a double convex lens is used.
4) The image acts like an object for the eye lens. Hence final image due to eye is formed at retina.
Here object distance (u)=-25 cm
Image distance(v) = distance of near point =-d
f is the focal length of bi-convex lens.
We known, `(1)/(f)=(1)/(v)-(1)/(u)implies(1)/(f) = (1)/(-d)-(1)/(-25)implies(1)/(f)=(1)/(-d)+(1)/(25)implies(1)/(f)=(d-25)/(25d)`
5) If d `gt` 25, then f becomes positive, it indicates that we need to used biconvex lens.